One of the main features that you can group nutritional supplements by is if they are water soluble or fat soluble.
Fat soluble vitamins not only need fat present to be properly metabolized, but when you take in more than what your cells need of a fat soluble vitamin, excess is squirreled away in your fat stores. From here, it can be slowly released back into your blood stream when needed.
Water soluble nutrients are easier to metabolize and when you take too much, the excess is excreted in your urine.
With water soluble vitamins, over dosing is hard, but it’s not impossible.
The most commonly known Water Soluble vitamin, probably is Vitamin C.